Ghost Shader

shader.glsl

vec4 colorAt(in vec2 coord, in int channel) {      
    if (channel == 0) return texture2D(iChannel0, coord.xy / iChannelResolution[0].xy);
    if (channel == 1) return texture2D(iChannel1, coord.xy / iChannelResolution[1].xy);
    if (channel == 2) return texture2D(iChannel2, coord.xy / iChannelResolution[2].xy);
    if (channel == 3) return texture2D(iChannel3, coord.xy / iChannelResolution[3].xy);
}

float monochrome(in vec4 color) {
    return (color.r + color.g + color.b) / 3.0;
}

vec4 lighten(in vec4 color, in float degree) {
    return vec4(
        clamp(color.r * degree, 0.0, 1.0),
        clamp(color.g * degree, 0.0, 1.0),
        clamp(color.b * degree, 0.0, 1.0),
        1.0
    );
}

void mainImage( out vec4 fragColor, in vec2 fragCoord)
{
    vec4 baseColor = colorAt(fragCoord, 0);
    float lightFactor = monochrome(colorAt(fragCoord, 1)) + 0.5;
    fragColor = lighten(baseColor, lightFactor);
}